You should check out the Moots fitment guide or speak to your local dealer.

I was going to chose the custom-fit option, only found out a 16.5" frame was 99% right. Needless to say, its been the best I've ever ridden.

I'm about 175cm tall, but I think the right size frame also has alot to do with the length of your arms and legs etc. So its probably worth filling in the custom sheet and seeing what they come back with.